1. Field of the Invention
The invention relates generally to a conveyor for articles comprising a plurality of cyclically operating pusher mechanisms for moving the articles from a first position through a predetermined arcuate path to a second position. More specifically, the invention relates to an apparatus for adjusting the phase of operation of each pusher mechanism in the conveyor.
2. Description of the Prior Art
Apparatus for placing newly formed glassware or other articles onto a moving conveyor are well known in the prior art. Such devices are herein called pusher mechanisms and the associated conveyor is called a pusher conveyor. These mechanisms generally operate cyclically in timed relationship with a glassware forming or other machine to move one or more articles from a first position to a second position.
Glassware forming machines are chosen as a means of illustrating the operation of prior art pusher conveyors. It will be understood, however, that other machines may employ similar devices. Typically, glassware forming machines comprise a plurality of sections operating cyclically in timed relationship with each other so that one or more finished articles are placed on a deadplate in timed relationship. Conveyors comprising a plurality of pusher mechanisms (each associated with a corresponding machine section) are used to move the glassware from each deadplate onto the conveyor. These pusher mechanisms operate cyclically in timed relationship with their associated sections and their phase relative to each other is critical.
Pusher mechanisms generally include a pneumatic pusher cylinder or head and a rotary actuator means for moving it through a predetermined arcuate path. Each pusher cylinder piston is operatively connected to a plurality of pusher fingers for contacting the articles to be moved. The pusher cylinder and fingers are in a retracted position prior to the deposition of the glassware articles on a corresponding deadplate. Extension of the piston by conventional means positions fingers near the glassware articles. Movement of the pusher cylinder through an arcuate path is an operating stroke which causes the fingers to contact the ware and move it outwardly through an angle of approximately 90.degree. onto a moving conveyor. The fingers are then retracted to clear the articles and the pusher cylinder returned inwardly on a return stroke in the opposite arcuate direction to complete the cycle.
The rotary actuator means used in prior art conveyors is often a drive or actuating cam driven by a common drive shaft. Each pusher mechanism has a single cam associated with it and the axial position of one cam relative to other cams on the drive shaft controls the phase of operation of the pusher mechanisms. Numerous patents show the use of a cam and cam follower roller as a rotary actuator: U.S. Pat. No. 3,324,986 (showing a rack and pinion connection to the pusher mechanism); U.S. Pat. Nos. 3,249,200 and 3,764,284 and 3,812,690 (sprocket and chain); and U.S. Pat. No. 3,679,041 (showing a connecting link between the pivot arm and the vertical shaft of the pusher).
Adjustment of each cam is sometimes necessary to change the point in the machine cycle when the cam begins or finishes causing the arcuate motion of the associated pusher mechanism. The cams must occasionally be adjusted even after the machine has been running for some time. The manufacturing tolerances of the various components in the conveyor are such that even precise assembly and installation often produces the need for minor adjustments of one or more of the cams in order to enable the various pusher mechanisms to interdigitate the articles in proper sequence on the conveyor. Taken together the pushers create an interdigitated succession of ware on the conveyor. In order to maintain efficiency and avoid disruptive temperature changes caused by stopping the machine, cam adjustments are often made while the conveyor is running; a procedure which is difficult and imprecise as well as hazardous. Futhermore, cams need to be adjusted for a job change in order to accommodate different size ware. U.S. Pat. No. 3,595,365 shows a mechanical (stop screw) adjustment means for adjusting the oscillating movement of individual pushers without stopping the conveyor. This mechanical means is, however, inefficient and necessarily subject to wear. Additionally, such a mechanism does not lend itself to integration with electronic control systems which are rapidly becoming indispensable. Consequently, there is a need for an efficient means of adjusting each cam while the machine is running.
Recently, electronic pusher mechanisms have been produced where each pusher mechanism may be driven independently of the others according to a predetermined velocity profile by an individual electric motor controlled by a common control means. Examples of such prior art electronic pushers are shown in U.S. Pat. Nos. 4,203,752 and 4,313,750. Each of these prior art electronic pushers requires a relatively large electric motor in driving connection with the pusher cylinder in order to control its arcuate movement in both directions. Because the pusher cylinder is a relatively massive component these motors are necessarily large and require high torque, thus making these electric pusher mechanisms costly and inefficient. Moreover, these mechanisms are not easily adaptable to existing mechanical pusher conveyors. Conversion of an existing pusher conveyor (utilizing a plurality of cams) to a conveyor having independently controllable electric pusher mechanisms requires costly replacement of each pusher mechanism and the elimination of the entire common drive shaft and associated components. Even conversion to known mechanically adjustable pusher mechanisms (as shown in aforementioned U.S. Pat. No. 3,595,365) requires replacement of each pusher mechanism.
Accordingly, it is an object of this invention to produce an apparatus adaptable to mechanical pusher conveyors enabling the individual independent control of phase adjustments of the cam of each individual pusher mechanism.
It is a further object of this invention to facilitate the retrofitting of existing mechanical conveyors without the necessity of dismantling or replacing same.
It is a further object of this invention to provide an apparatus for individually adjusting the cams of a mechanical pusher conveyor by a control unit selectively connectable to the particular pusher mechanism to be adjusted.
It is a further object of this invention to provide an apparatus for individually adjusting the cams of a mechanical pusher conveyor by a computer control including cam position sensing for feedback of current cam position which when compared with the computer set up data forms the basis for a cam position correction signal.